netdev - RE: [PATCH net-next v2 2/6] net: txgbe: Implement I2C bus master driver

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Message-ID: <024701d970db$17335890$459a09b0$@trustnetic.com>
Date:   Mon, 17 Apr 2023 11:17:07 +0800
From:   Jiawen Wu <jiawenwu@...stnetic.com>
To:     "'Wolfram Sang'" <wsa@...nel.org>,
        "'Jarkko Nikula'" <jarkko.nikula@...ux.intel.com>
Cc:     <netdev@...r.kernel.org>, <linux@...linux.org.uk>,
        <linux-i2c@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
        <mengyuanlou@...-swift.com>
Subject: RE: [PATCH net-next v2 2/6] net: txgbe: Implement I2C bus master driver

On Friday, April 14, 2023 7:05 PM, Jiawen Wu wrote:
> On Friday, April 14, 2023 12:29 AM, Wolfram Sang wrote:
> > > > > Implement I2C bus driver to send and receive I2C messages.
> > > > >
> > > > > This I2C license the IP of Synopsys Designware, but without interrupt
> > > > > support on the hardware design. It seems that polling mode needs to be
> > > > > added in Synopsys Designware I2C driver. But currently it can only be
> > > > > driven by this I2C bus master driver.
> > > > >
> > > > > Signed-off-by: Jiawen Wu <jiawenwu@...stnetic.com>
> > > > > ---
> > > > >   drivers/net/ethernet/wangxun/Kconfig          |   1 +
> > > > >   .../net/ethernet/wangxun/txgbe/txgbe_phy.c    | 153
> > > > > ++++++++++++++++++
> > > > >   .../net/ethernet/wangxun/txgbe/txgbe_type.h   |  23 +++
> > > > >   3 files changed, 177 insertions(+)
> > > > >
> > > Looks like your use case has similarities with the commit 17631e8ca2d3
> > > ("i2c: designware: Add driver support for AMD NAVI GPU").
> >
> > Yes, can you please check if you can't use the current i2c designware
> > driver?
> 
> Hi Jarkko & Wolfram,
> 
> I read the i2c designware driver code, and found that 'dev->ss_hcnt' can
> only be obtained by i2c_dw_acpi_configure() or calculated by clock rate.
> 
> I don't quite understand how to get the clock rate. I tried to add a software
> node of clock with property ("clock-frequency", 100000) and referenced by
> I2C node. But it didn't work.
> 
> Can I deliver 'dev->ss_hcnt' via platform data? Or how should I fill in the
> software node?
> 

The above question is in the case of platform driver.

Moreover, why 'dev->fs_hcnt' and 'dev->fs_lcont' must be set when I use the
standard mode? Should it be set only if I2C_MAX_FAST_MODE_* ?